United Kingdom patent application No. 2,071,650, discloses that .beta.-lactams having a sulfonic acid salt substituent (--SO.sub.3.sup..crclbar. M.sup..sym., wherein M.sup..sym. is hydrogen or a cation) in the 1-position and an acylamino substituent in the 3-position, have antibacterial activity. Claim 17 of the patent application discloses .delta.-lactams having the formula ##STR3## wherein R.sub.i is acyl; R.sub.ii is hydrogen or alkoxy of 1 to 4 carbon atoms; R.sub.iii and R.sub.iv are the same or different and each is hydrogen or alkyl, cycloalkyl or phenyl; and in addition where one of R.sub.iii or R.sub.iv is hydrogen, the other can be alkenyl, styryl, alkynyl, alkoxy, alkylthio, carboxyl or an alkyl ester thereof, hydroxymethyl, lower alkylsulfonylmethyl, phenylsulfonylmethyl, wherein the phenyl group may be substituted with methyl or halogen, halomethyl, mercaptomethyl or a benzyl or triphenylmethylthio derivative thereof, azidomethyl and aminomethyl; and M.sup..sym. is hydrogen or a cation.
European patent application No. 0-053-816 discloses antibacterial .beta.-lactams having the formula ##STR4## and salts thereof, wherein R.sub.v is inter alia, acylamino, R.sub.vi is hydrogen or methoxy and R.sub.vii is a "a residue derived from an organic compound by removal of one hydrogen atom attached to a carbon atom thereof". More specifically, R.sub.vii can be, inter alia, --CH.sub.2 --O--CH.sub.3 (examples 41 and 47).